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Blasting a Design with Power Mosfet Models

D

D from BC

Jan 1, 1970
0
There's a wide variety of power mosfets all with complicated dynamics.

Has anyone created a large modern mosfet spice library for LTspice
with models from many sources...
Then set up LTspice to try each mosfet model one after another with
results all together on one graph. (If capable..)
That way the optimum mosfet can be found for a given application..

The mosfet library file can made smaller by only having mosfets with
V,I, and P specs that suit the app.

Something like that is going to have a long run time but the computer
can run while I'm sleeping.. :)

Comments...?
D from BC
 
W

Winfield Hill

Jan 1, 1970
0
There's a wide variety of power mosfets all with complicated dynamics.

Has anyone created a large modern mosfet spice library for LTspice
with models from many sources...
Then set up LTspice to try each mosfet model one after another with
results all together on one graph. (If capable..)
That way the optimum mosfet can be found for a given application..

The mosfet library file can made smaller by only having mosfets with
V,I, and P specs that suit the app.

Something like that is going to have a long run time but the computer
can run while I'm sleeping.. :)

If you use Spice power MOSFET models to select a suitable MOSFET
for a design you are likely to be disappointed. That's because
there's scarcely a perfect power MOSFET Spice model out there,
and the few really good ones work well primarily only for certain
aspects they were optimized to be good at. Most, if not all,
are downright awful when compared against certain types of bench
measurements. You'll be much better off studying datasheets and
performing the relevant circuit calculations with the MOSFET data.
 
D

D from BC

Jan 1, 1970
0
If you use Spice power MOSFET models to select a suitable MOSFET
for a design you are likely to be disappointed. That's because
there's scarcely a perfect power MOSFET Spice model out there,
and the few really good ones work well primarily only for certain
aspects they were optimized to be good at. Most, if not all,
are downright awful when compared against certain types of bench
measurements. You'll be much better off studying datasheets and
performing the relevant circuit calculations with the MOSFET data.

I'm just discovering that..
I got the Infineon library and tried the SPA21N50 model (it's a
subckt) in LTspice. All I get is singular matrix errors in my app.
If I use a VDMOS mosfet model (LTSpice), it's ok.

It should be possible someday to do a "run all mosfets" routine in
spice..
I was just curious if there was a lazy way to compare power
dissipation between power mosfets operating above 100khz.

Well... back to the traditional method...Math, datasheets and bench
testing.
Until the models and software get better :)

D from BC
 
W

Winfield Hill

Jan 1, 1970
0
I'm just discovering that..
I got the Infineon library and tried the SPA21N50 model (it's a
subckt) in LTspice. All I get is singular matrix errors in my app.
If I use a VDMOS mosfet model (LTSpice), it's ok.

It should be possible someday to do a "run all mosfets" routine
in spice..
I was just curious if there was a lazy way to compare power
dissipation between power mosfets operating above 100khz.

Well... back to the traditional method...Math, datasheets and
bench testing.
Until the models and software get better :)

D from BC


You left out using the manufacturer's tables of their
MOSFET properties to pick out candidate parts. These
should have reasonably-low, but not too low Ron, and
not too high Ciss, etc. Select a preferred package
and see if it's available in stock anyplace. Etc.
 
D

D from BC

Jan 1, 1970
0
You left out using the manufacturer's tables of their
MOSFET properties to pick out candidate parts. These
should have reasonably-low, but not too low Ron, and
not too high Ciss, etc. Select a preferred package
and see if it's available in stock anyplace. Etc.

Shopping for mosfets is like shopping for music...Not too hard and not
too soft.. :)

I do use the web tables to narrow down the search but there can be
still many candidates per manufacture..

Who's on top now in producing mosfets approaching the ideal high speed
power switch? (+100W application). Maybe I can just focus on one
manufacture...say Fairchild??
D from BC
 
H

Henry Kiefer

Jan 1, 1970
0
|
| Shopping for mosfets is like shopping for music...Not too hard and not
| too soft.. :)
|
| I do use the web tables to narrow down the search but there can be
| still many candidates per manufacture..
|
| Who's on top now in producing mosfets approaching the ideal high speed
| power switch? (+100W application). Maybe I can just focus on one
| manufacture...say Fairchild??

As far as I can tell Fairchild is one of the topmost candidates (if cost is included).
I recognized that every manufacturer specialized in specific subfields here.

Would be a nice feature for LTspice to run libraries as batch for comparision.

- Henry
 
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